It is known that adrenocortical hormones, though not having a direct inhibitory effect on phospholipase A.sub.2, secondarily exhibits anti-inflammatory effects by inducing production of an anti-inflammatory protein within the cells. However, there is a problem of great clinical importance that an extended use of adrenocortical hormones at high doses causes serious side effects including reduction of glucose tolerance, aggravation of infections, delayed healing of wounds, formation of steroid cataract and induction of glaucoma. Thus, to separate the side effects of adrenocortical hormones from their therapeutic effects is highly desired.
In order to separate the side effects from the therapeutic effects, which are both aspects of the adrenocortical hormonal effects, therefore, agents with adrenocortical hormonal effects must not be overdosed. It is thus considered important to find an adjuvant molecule that can augment adrenocortical hormonal effects, in particular, an adjuvant molecule that can augment adrenocortical hormones-mediated gene expression.
No agent, however, has been known so far to serve as as an adjuvant molecule that is safe and capable of augmenting adrenocortical hormones-mediated gene expression, and there has been a need for an agent that can augment adrenocortical hormonal effects.
Thus, a study was carried out that was directed to reducing the side effects of adrenocortical hormones by combining them with another, adjuvant molecule, thereby allowing to lower the concentration of adrenocortical hormones. The study revealed that a certain group of phosphodiester compounds were capable of augmenting adrenocortical hormonal effects (Japanese Unexamined Patent Publication No. H09-194376).
Upon the above background, however, the present inventors, from a different viewpoint, pursued a study in search of an agent that can directly reduce the side effects of adrenocortical hormones not by reducing their dose (or their concentration in a preparation). In the process, the above phosphodiester compounds were further studied on their interaction with adrenocortical hormones. As a result, it was surprisingly found by the present inventors that those phosphodiester compounds and adrenocortical hormones, when concurrently administered, exhibit a synergism of the antiinflammatory effects of the respective agents, as opposed to simple addition of their effects. At the same time, it was also unexpectedly found that the side effects of the adrenocortical hormones were directly and remarkably reduced. The present invention was made upon this findings.